The invention relates to the switching regulator art in which a switch duty cycle controls the energy transfer in a power supply. The fundamental operation of such devices is set forth in a paper titled Scaling Down PWM Chip Suits Low-Power Switchers in the July 8, 1982, issue of Electronic Design, pages 175-179. This paper sets forth the fundamental details of buck, boost, and flyback power supply circuits. Another paper in the same issue of Electronic Design, on pages 69-80, is titled Power-Supply ICs Gain in Function, Programmability and shows how FET switches are employed.